1. Technical Field
The present invention relates to a liquid ejecting apparatus.
2. Related Art
There is known a liquid ejecting apparatus which includes an ejecting unit for ejecting a liquid and a liquid storing unit for storing a liquid. As this kind of liquid ejecting apparatus, for example, an ink jet printer (hereinafter, a printer) is known. A printing head (hereinafter, a head) of the printer corresponds to the ejecting unit, and an ink cartridge thereof corresponds to the liquid storing unit.
In the printer, generally, the consumption state of the ink cartridge is detected. The ink consumption state may be detected by using a technology disclosed in Japanese Patent No. 3,824,216.
In order to drive the head, generally, a head waveform (signal) as a voltage waveform for driving the head is required. In addition, in order to detect the ink consumption state of the ink cartridge mounted with a piezoelectric element, an ink detecting waveform (signal) as a voltage waveform for the piezoelectric element is required. As a printer requiring these kinds of waveforms, there is a printer 100 shown in FIG. 1A.
The printer 100 includes a control unit 101, a DAC (Digital Analog Converter) circuit 102, a head driving circuit 103, and an ink detecting circuit 104.
The control unit 101 includes a creating unit 1011 which creates head waveform data and a creating unit 1012 which creates ink detecting waveform data.
The DAC circuit 102 includes a waveform creating circuit 1021. The waveform creating circuit 1021 is a circuit which is able to create both the head waveform and the ink detecting waveform.
In detail, when the waveform creating circuit 1021 receives the head waveform data created by the creating unit 1011, the waveform creating circuit 1021 creates the head waveform on the basis of the data, and outputs the waveform to the head driving circuit 103. The head driving circuit 103 drives the head in accordance with the waveform.
On the other hand, when the waveform creating circuit 1021 receives the ink detecting waveform data created by the creating unit 1012, the waveform creating circuit 1021 creates the ink detecting waveform on the basis of the data, and outputs the waveform to the ink detecting circuit 104. The ink detecting circuit 104 detects the ink consumption state in accordance with the waveform.
The waveform creating circuit 1021 is not able to simultaneously create and output the head waveform and the ink detecting waveform due to the condition of the circuit. For this reason, it is not possible to detect the ink consumption state while the head waveform is output. On the contrary, it is not possible to drive the head while the ink detecting waveform is output. In addition, since the head waveform and the ink detecting waveform are basically different from each other, it is not possible to use them as a common waveform.
In order to determine whether the ink required for a predetermined unit of printing process (for example, one pass printing process) remains, the ink consumption state is detected before the predetermined unit of printing process is started. However, in this case, since the head driving start timing is delayed due to the above-described reasons, there is concern that the time required for the printing process may be extended. In detail, as shown in FIG. 1B, the ink consumption state detecting process is started (at a time point T1) when the precedent pass printing process is completed, and the subsequent pass printing process is started (at a time point T3) after the detecting process is completed (at a time point T2).
In addition, when the ink supply is performed during the predetermined unit of printing process, ink is exhausted during the printing process, and hence there is concern that ink may leak from an ink ejecting port of the head. Particularly, in the case of a so-called large printer, it is thought that such problems more easily occur compared with other types of printers.
The above-described problem may arise in other types of liquid ejecting apparatuses as well as the printer.